PRIMARY OBJECTIVES: Description and analysis of neuropsychological deficits following brain trauma with diffuse lesion probably corresponding to diffuse axonal injury (DAI).RESEARCH DESIGN: A series of 111 patients suffering from traumatic brain injury could be investigated neuropsychologically within the first 4 weeks after injury and re-assessed after 5-8 months. They included 11 subjects with CT-evidence of diffuse axonal injury, but no CT-signs of focal contusions. Eleven patients with focal frontal contusions but no CT signs of DAI were matched to and compared with the DAI subjects. Seventeen TBI patients with normal CT scans served as controls.RESULTS: When assessed within the first 4 weeks after TBI, both DAI and frontal contusion patients exhibited behavioural abnormalities and deficits in Wechsler Similarities. The DAI patients were also impaired in Digit Span backward and Stroop interference. When re-assessed, the DAI patients showed considerable deficits in the California Verbal Learning Test and in the Wisconsin Card Sorting Test.CONCLUSIONS: DAI leads to neuropsychological impairment dominated by executive and memory dysfunction.